iMovie crashes

Hi, ineilh,

First, check to see that you have enough free space on your external drive for iMovie to function . 10 GB should be enough. If all is well there, nothing to do but try some diagnostics to see if you can isolate the problem. Here are some diagnostic procedures that you can try.

Deleting Preferences

Open iMovie while holding down the Option

and Command keys and select to delete preferences in the box that appears.

iMovie will open in a new library. Reopen your old library to get back to your

projects.

Opening iMovie in a new library

Try opening iMovie in a new library.  To do that, open iMovie while holding down

the Option key and then selecting to create a new library in the box that

appears.

Opening iMovie in a new user account

Create a new user account from System

Preferences/Users and Groups and try to open and use iMovie in the new account.

New Project

Another thing you can try is to copy your

media into a newly created project and see if that cures the problem. To do

that, do an Edit/Select All, Edit/Copy, of the media in your project and then

Edit/Paste it into the newly created project.

Safe Mode

You could also try booting up in Safe

Mode (see Finder menu for instructions) and, after everything loads,

immediately shut down and reboot in normal mode. Then see if iMovie works

properly.

Updating iMovie

To update/redownload iMovie 10, drag your

iMovie 10 app from the Applications folder into the trash, but do not empty the

trash. (You can skip that step if you had iMovie 10 on your computer before,

but deleted it.) Sign in to the app store and open your purchases folder by

clicking on your name at the bottom of the app store side bar. (NOTE: For El

Capitan and older, click on the Purchases tab at the top of the app store

screen and then sign in. Click on Purchases again to reveal your

purchases.)  You will see your purchases

displayed, including iMovie 10. Redownload/update iMovie from there. If not

successful, drag your present iMovie app out of the trash (if you moved it

there) and return it to the Applications folder.

Resetting the System Management Controller

Try resetting the System Management

Controller:

https://support.apple.com/en-us/HT201295

 Resetting the NVRAM or PRAM

Try resetting the NVRAM or PRAM,

although this issue would be fairly rare:

https://support.apple.com/en-us/HT204063

-- Rich